WO 2009/058752 A1 discloses an apparatus for receiving system information updates including a wireless transmit receive unit, WTRU, being configured to receive a system frame number. The WTRU is also configured to receive system information messages in a modification period. The modification period has a boundary determined by the system frame number. The WTRU is configured to receive system information change notification after a first modification change boundary and determines that the system information is valid until a second modification change boundary.
US 2012/0188878 A1 discloses the transmission of primary and secondary control information for user equipment, UE, to operate in a wide area SFN and a local area SFN respectively. The first control information is transmitted over the wide area SFN whereas the second control information may be transmitted over the local SFN or a dedicated channel. The first control information may contain scheduling of the second control information and the second control information may be different in different local areas within the same SFN. Local SFNs use distinct pilots or other physical channel parameters to give UEs a chance to distinguish between local SFNs. Furthermore a method to transmit local SFNs and UEs to receive these in awareness of the different SFNs and utilizing means to distinguish different SFNs is provided.
US 2008/0025240 A1 discloses first transmissions of data over an SFN and second transmissions or re-transmissions of the same data in non-SFN manner scheduled so that re-transmissions do not disturb reception of further SFN-transmissions.
US 2013/0029706A1 discloses a wireless spectrum sharing using SFN at a certain transmission power, wherein no position dependent resource usage is provided in an SFN.
WO 2009/124261 A2 discloses the provision of a program guide via an SFN that spans over the coverage area of one or more Multiple Frequency Networks MFNs and provides information about content and frequency of transmissions of the MFNs.
US 2014/0226638A1 teaches a detection of a system information broadcast in an SFN.
A further network arrangement is described in JP 2009-246860 in which a combination of directional base station transmitters and timing offsets is used. By employing directional antennas, only a relatively small region of signal overlap from neighbouring base stations results and in this region, through use of transmission timing offsets, signals from two base stations are received in this overlap region with a small time offset.
Wireless communication systems are known, which are widely deployed to provide various types of communication content to several types of end devices. Such systems may be multiple-access systems capable of supporting communication with multiple users by sharing the transmission resources, such as a frequency per time slot or in general bandwidth. Known multiple access systems are referred to as code division multiple access CDMA systems, time division multiple access TDMA systems, frequency division multiple access FDMA systems, family members of the Long Term Evolution LTE family of standards such as LTE-A and furthermore orthogonal frequency division multiple access, OFDMA, systems.
A wireless multiple access communication system supports communication for multiple wireless terminals simultaneously. A wireless communication network may include a number of base stations that can support communication for a number of wireless devices. Wireless devices comprise user equipment and remote end devices. An SFN is a broadcast network where several transmitters simultaneously transmit the same signal over the same frequency channel or over the same range of frequencies (e.g., in case of OFDMA systems such as LTE/LTE-A, over the same range of sub carrier frequencies) to user equipment. A simplified form of SFN can be established by a low power co-channel repeater, booster or broadcast translator. The aim of an SFN is efficient utilization of the radio spectrum and the avoidance of signalling efforts for handovers. An SFN also increases the coverage area compared to a Multiple Frequency Network MFN, since the total received signal strength may increase in positions between the transmitters.
In known cellular mobile radio systems, the currently existing so-called Macro Cell network topology is enhanced by the establishment of smaller radio cells, the so-called “small cells”. This evolution from a homogeneous to a heterogeneous network topology is performed by installing additional base stations providing cells of small range. The mobile network operators are currently focusing primarily on the most frequented hot spots, such as train stations, shopping centres, and the like, in which a large number of mobile users are constantly present Macro cells and small cells can be operated in different frequency ranges. A macro cell layer can be established, usually by means of lower frequencies, and small cell layers are usually operated at higher frequencies. The small cells can be connected via backhaul connections to the core network of the mobile network operator.
User equipment can be transferred both within a layer as well as between a macro cell layer and a small cell layer by means of a cell handover procedure. Such a handover is based at least on the reception of basic cell specific information as well as the measurement of received field strengths being measured on the downlink reference signals, which are performed according to a predefined configuration in the mobile device. The measurement results are transmitted from the mobile end device to the serving base station, the so-called “serving eNB”. During known handover procedures, the new radio cell, the so-called “target eNB”, is prepared for the upcoming handover of the mobile device. This is performed by means of backhaul connections in the core network, in case of LTE via an S1 interface or between the involved base stations, in case of LTE via an X2 interface.
According to the prior art signalling overhead results from each of the cell handover procedures according to three aspects: on the air interface, in the Radio Access Network (RAN), and the Core Network (CM). Furthermore handover procedures require computing power, also in three ways: in the mobile device, in the involved base stations, and the core network. In addition, delays on the bandwidth-limited transmission paths of the networks are generated.
Due to these disadvantages, mobile devices, which are moving quickly, should not be passed frequently from one cell to another. As a result fast moving mobile devices are often kept on the macro cell layer. Thus, fast moving mobile devices often cannot benefit from the advantages the small cell layer offers.